1. Field of the Invention
This invention relates to a cosmetic lotion, cream or ointment, and, more particularly, to a cosmetic non-irritating, texture enhancing, homogenized composition for rejuvenating the appearance of skin or hair without irritation or damage which is a flowable, micronized composition having a pH of from 1 to 6.5, more desirably 3-4, and which comprises a micronized, homogenized, lightly crosslinked N-vinyl lactam polymer hydrogel and a rejuvenating agent selected from the group consisting of a carboxylated hydrocarbon optionally mono- or poly-substituted with a carbonyl or hydroxy group and an ammonium or alkali metal salt thereof or mixtures of said acids or acid and salts, or an aqueous, alcoholic or aqueous-alcoholic solution of said composition.
2. Description of the Prior Art
Cosmetic compositions having an alpha- or beta-hydroxy acid (AHA/BHA) as the active ingredient are well-known in the art. These compositions are useful in the treatment of the skin, particularly for anti-aging, skin smoothing, improvement in skin tone, reduction of fine lines, enhancement and control of desquamation in individuals with hyperkeratosis and the like. Application of such compositions generally results in a younger-looking skin as new cells replace the old. Smith, in Soap/Cosmetics/Chemical Specialties, Sept. 1993, page 54, addressed the question of whether an AHA must be in the acid form to be effective in promoting exfoliation and skin renewal. Various acids were examined for their ability to increase cell renewal at different pHs, with similar results observed for all acids tested. As the pH increased, the ability to stimulate cell renewal diminished; in fact, at a pH above 6, very little if any stimulation of the skin was observed with any AHA compounds. For the acids tested at selected pH levels, a maximal stimulation of renewal was observed at a pH of about 3, as shown in Table 1 below.
TABLE 1 ______________________________________ Relationship between Cell Renewal, Irritation & pH for Various Acids Tested TEST MATERIAL pH CELL RENEWAL* IRRITATION* ______________________________________ 4% Lactic acid 3 35 2.8 5 24 2.1 7 13 1.2 4% Glycolic acid 3 34 2.9 5 23 2.1 7 10 1.1 4% Salicylic acid 3 42 3.0 5 28 2.3 7 12 1.2 5% Citric acid 3 18 2.3 5 14 2.1 7 8 1.1 ______________________________________ *A higher number indicates improved cell renewal/more irritation
Accordingly, to achieve improvement in skin condition, it has been necessary for the user to endure accompanying skin irritation caused by the presence of effective amounts of the acid. Accordingly, skin irritation is a major concern in the formulation of alpha and beta-hydroxy acid-containing products, particularly at acid loading levels which can deliver faster and more effective skin peeling which can be as high as, e.g. 45% to achieve chemical defoliation of the skin.
Goldenberg, R., in DCI/Jan. 1995, pages 37-44, entitled "Minimizing Irritation in Cosmetic Foundations", at page 42, stated that "PVP doesn't have the glamour botanical image of herbal extracts, but it has been reported to work effectively as an anti-irritant (at 1 percent) in a pH 3.0 polyvinyl alcohol mask containing 8 percent lactic acid as a moisturizer. A problem in all this is that hardly anyone has published AHA irritation studies".
Accordingly, it is an object of this invention to provide a cosmetic composition for the rejuvenation of skin or hair with substantially no irritation during use pH levels of 4 or below.
It is another object of this invention to provide a cosmetic composition for reducing hair dryness and rejuvenation of the hair appearance by reducing conditioner build-up.
Another object is to provide an improved thickener for liquid formulations.
Still another object is to provide a non-irritating, rejuvenating skin composition containing high concentrations of acid or a salt thereof.
These and other objects and features of the invention will become apparent from the following description and disclosure.